Sterol blends as an additive in asphalt binder

ABSTRACT

Disclosed are asphalt binder compositions and methods for making such compositions with pure sterol:crude sterol blends. The sterol blends improve various rheological properties.

PRIORITY

This application is a continuation of U.S. patent application Ser. No.16/323,883, filed Feb. 7, 2019, which claims priority to InternationalApplication No. PCT/US2017/045887, filed on Aug. 8, 2017, which claimsthe benefit of U.S. Provisional Patent Application Ser. No. 62/372,504,filed Aug. 9, 2016, the entire disclosures of which are incorporated byreference for all purposes.

BACKGROUND

Asphalt pavement is one of the most recycled materials in the world,finding uses when recycled in shoulders of paved surfaces and bridgeabutments, as a gravel substitute on unpaved roads, and as a replacementfor virgin aggregate and binder in new asphalt pavement. Typically, useof recycled asphalt pavement h limited to sub-surface pavement layers orto controlled amounts in asphalt base and surface layers. Such uses arelimited in part because asphalt deteriorates with time, loses itsflexibility, becomes oxidized and brittle, and tends to crack,particularly under stress or at low temperatures. These effects areprimarily due to aging of the organic components of the asphalt e.g.,the bitumen-containing binder, particularly upon exposure to weather.The aged binder is also highly viscous. Consequently, reclaimed asphaltpavement has different properties than virgin asphalt and must beprocessed in such fashion that the properties of the aged binder don'timpact long term performance.

To reduce or retard the impact of asphalt aging on the long-rangeperformance of mixtures, numerous materials have been investigated. Forexample, rejuvenators are marketed with a stated goal of reversing theaging that has taken place in recycled raw materials such as reclaimedasphalt pavement (RAP) and/or reclaimed asphalt shingles (RAS). It isunlikely that rejuvenation of asphalt can actually occur and foe morelikely scenario is that these additives may instead serve as softeningagents for the virgin binders employed in mixtures containing RAP and/orRAS. In some instances, 10% or more by weight of these softening agentsare added to foe virgin binder when such mixtures are produced.

Aging can be assessed by measuring ΔTc, the difference between theStiffness critical temperature and the creep critical temperature afteraging. The use of softening agents can produce a mixture with recoveredbinder properties that have acceptable values of ΔTc after extendedmixture aging, but these acceptable binder properties after aging comeat the cost of producing a mix that can be quite low in stiffness duringthe pavement's early life.

SUMMARY

Disclosed are compositions and methods that may retard, reduce orotherwise improve the effects of aging in recycled or reclaimed asphaltto preserve or retain some or all of the original virgin asphalt binderproperties.

In one embodiment, the present disclosure provides a method forretarding the aging of or restoring aged asphalt binder comprising:

-   -   adding a pure sterol:crude sterol blend to an asphalt binder        composition, wherein the asphalt binder composition comprises a        virgin asphalt binder, aged asphalt binder or both, and wherein        the sterol blend comprises a 10:90 to 90:10 weight ratio of pure        sterol to crude sterol.

In one embodiment, the present disclosure provides a method for reusingaged asphalt for asphalt binder pavement production, comprising adding apure sterol:crude sterol blend to an asphalt binder composition, whereinthe asphalt binder composition comprises a virgin asphalt binder, agedasphalt binder or both, and wherein the sterol blend comprises a 10:90to 90:10 weight ratio of pure sterol to crude sterol.

In another embodiment, the present disclosure provides an asphalt binderpaving composition comprising virgin asphalt binder, aged asphaltbinder, or both and a pure sterol:crude sterol blend, wherein the sterolblend comprises a 10:90 to 90:10 weight ratio of pure sterol to crudesterol.

In still other embodiments, the present disclosure provides a method forrestoring aged asphalt binder comprising adding a pure sterol:crudesterol blend to a reclaimed asphalt binder, wherein the sterol blendcomprises a 10:90 to 90:10 weight ratio of pure sterol to crude sterol.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 depicts a representative plant sterol structure e.g.,beta-sitosterol.

FIG. 2 is a graphical representation showing stiffness and creeptemperature results for Re-refined Engine Oil Bottoms (REOB) blends withsterols.

FIG. 3 shows exemplary plant sterols.

FIG. 4 is a graphical representation showing Stiffness, m-Value CriticalTemperatures and ΔTc for PG 64-22 with 8% REOB and 10% of blends of talloil pitch and sterol at varying concentrations.

FIG. 5 is a graphical representation comparing ΔTc for PG 64-22+8%REOB+three levels of pure sterol with PG 64-22+8% REOB.

DETAILED DESCRIPTION

The disclosed asphalt compositions contain anti aging (viz., agereducing or age retarding) sterol blends that help in the preservation,recycling and reuse of asphalt compositions. The asphalt compositionspreferably are free of cyclic organic compositions that contain estersor ester blends. The disclosed compositions have particular value forthe renewal of reclaimed asphalt, especially asphalt containingsoftening agents such as waste engine oils.

The disclosed asphalt compositions provide recycled asphalt binderswhich may have improved physical and rheological characteristics such asstiffness, effective temperature range, and low temperature properties.Some embodiments provide for the use of binder extracted from recycledasphalt pavement, recycled asphalt shingles or both in asphalt blends.Some embodiments provide for the addition of a sterol blend to minimizepotential detrimental low-temperature effects of recycled asphalt whileallowing for higher stiffness at high temperatures.

Headings are provided herein solely for ease of reading and should notbe interpreted as limiting.

Abbreviations, Acronyms & Definitions

“Aged asphalt binder” refers to asphalt or binder that is present in oris recovered from reclaimed asphalt. Aged binder has high viscositycompared with that of virgin asphalt or virgin bitumen as a result ofaging and exposure to outdoor weather. The term “aged binder” alsorefers to virgin asphalt or virgin binder that has been aged using thelaboratory aging test methods described herein (e.g. RTFO and PAV).“Aged hinder” may also refer to hard, poor-quality, orout-of-specification virgin binders that could benefit from addition ofthe disclosed blend particularly virgin binders having a ring-and-ballsoftening point greater than 65° C. by EN 1427 and a penetration valueat 25° C. by EN 1426 less than or equal to 12 dmm.

“Aggregate” and “construction aggregate” refer to particulate mineralmaterial such as limestone, granite, trap rock, gravel, crushed gravelsand, crushed stone, crushed rock and slag useful in paving and pavementapplications.

“Asphalt binder” refers to a binder material including bitumen andoptionally other components that is suitable for mixing with aggregateto make a paving mix. Depending on local usage, the term “bitumen” maybe used interchangeably with or in place of the term “asphalt” or“binder”.

“Asphalt pavement” refers to a compacted mixture of asphalt andaggregate.

“Asphalt paving mixture”, “asphalt mix” and “mix” refer to anuncompacted mixture of asphalt and aggregate. Depending on local usage,the terms “bitumen mix” or “bituminous mixture” may be usedinterchangeably with or in place of the terms “asphalt paving mixture”,“asphalt mix” or “mix”.

Bitumen” refers to a class of black or dark-colored (solid, semisolid,or viscous) cementitious substances, natural or manufactured, composedprincipally of high molecular weight hydrocarbons, of which asphalts,tars, pitches, and asphaltenes are typical.

“Crude” when used with respect to a material containing a sterol ormixture of sterols means sterol that has not been fully refined and cancontain components in addition to sterol.

“Neat” or “Virgin” binders are binders not yet used in or recycled fromasphalt pavement or asphalt shingles, and can include Performance Gradebinders.

“PAV” refers to a Pressurised Aging Vessel test. The PAV test simulatesaccelerated aging of asphalt using a pressurized aging vessel asdescribed in ASTM D6521-13, Standard Practice for Accelerated Aging ofAsphalt Binder Using a Pressurized Aging Vessel (PAV).

“Pure” when used with respect to a sterol or mixture of sterols meanshaving at least a technical grade of purity or at least a reagent gradeof purity.

“Reclaimed asphalt” and “recycled asphalt” refer to RAP, HAS, andreclaimed asphalt from old pavements, shingle manufacturing scrap,roofing felt, and other products or applications.

“Reclaimed asphalt pavement” and “RAP” refer to asphalt that has beenremoved or excavated from a previously used road or pavement or othersimilar structure, and processed for reuse by any of a variety ofwell-known methods, including milling, ripping, breaking, crushing, orpulverizing.

“Reclaimed asphalt shingles” and “RAS” refer to shingles from sourcesincluding roof tear-off, manufacture's waste asphalt shingles andpost-consumer waste.

“RTFO” refers to a Rolling Thin Film Oven Test. This is a test used forsimulating the short-term aging of asphalt binders as described in ASTM02872-12e1, Standard Test Method for Effect of Heat and Air on a MovingFilm of Asphalt (Rolling Thin-Film Oven Test).

“Softening agent” refers to additives that ease (or facilitate) themixing and incorporation of a recycled asphalt into fresh bitumen orinto an asphalt mix, during an asphalt mix production process.

“Sterol Wend” refers to a composition, mixture or blend of pure sterolsand crude sterols that can be combined with aged binder (e.g. recycledor reclaimed asphalt) to retard the rate of aging of asphalt binder, orto restore or renew rite aged binder to provide some or all of theoriginal properties of virgin asphalt or virgin binder.

“ΔTc” refers to the difference between the stiffness criticaltemperature and the creep critical temperature. The stiffness criticaltemperature is the temperature at which a binder tested according toASTM D6648 has a flexural creep stiffness value of 300 MPa and the creepcritical temperature is the temperature at which the slope of theflexural creep stiffness versus creep time according to ASTM D6648 hasan absolute value of 0.300. Alternatively the stiffness and creepcritical temperatures can be determined from a 4 mm dynamic shearrheometer (DSR) test and analysis procedures described by Sui, C.,Farrar, M., Tuminello, W., Turner. T., A New Technique for Measuringlow-temperature Properties of Asphalt Binders with Small Amounts ofMaterial, Transportation Research Record: No 1681, TRB 2010. See alsoSui, C., Farrar. M. J., Harnsberger, P. M., Tuminello, W. H., Turner, T.F., New Low Temperature Performance Grading Method Using 4 mm ParallelPlates on a Dynamic Shear Rheometer. TRB Preprint CD, 2011, where ritestiffness critical temperature b the temperature where the relaxationmodulus equals 143 MPa and the creep critical temperature is where theabsolute value of the slope of rite relaxation modulus master curveversus relaxation time equals 0.275.

All weights, parts and percentages are based on weight unless otherwisespecified.

Binders

Current bituminous paving practices involve the use of high percentagesof RAP and/or RAS as components in the bituminous mixtures being paved.Typically RAP concentrations can be as high as 50% and RASconcentrations can be as high as 6% by weight of the paving mixture. Thetypical bitumen content of RAP is in the range of 5-6% by weight and thetypical bitumen content of RAS is in the range of 20-25% by weight.Consequently, a bituminous mixture containing 50% by weight of RAH willcontain 2.5% to 3% RAP bitumen contributed to the final bituminousmixture and a bituminous mixture containing 6% RAS by weight wiltcontain 12% to 1.5% RAS bitumen contributed to the final bituminousmixture. In many instances RAP and/or RAS are combined in bituminousmixtures; for example 20% to 30% RAP and 5% to 6% RAS can beincorporated into a bituminous mixture. Based on rite typical theasphalt binder contents of RAP and/or RAS, asphalt binders containing20% to 30% RAP aid 5% to 6% RAS can result in 2% binder coming from theRAP and RAS combination to as much as 33% binder being derived from theRAP and RAS combination. Since a typical bituminous paving mixture willcontain about 5.5% total bitumen there can be about 36% to as much as60% of the total bitumen in the bituminous mixture from these recycledsources.

Characteristics of bitumen in these reclaimed sources relative to virginbinders used in bituminous mixtures are shown in Table 1. To determinethe ΔTc parameter, a 4 mm dynamic shear rheometer (DSR) test procedureand data analysis methodology from the Western Research Institute wasemployed (see Sui, C., Farrar, M., Tuminello, W., Turner, T., A NewTechnique for Measuring low-temperature Properties of Asphalt Binderswith Small Amounts of Material, Transportation Research Record: No 1681,TRB 2010. See also Sui, C., Farrar, M. J., Harnsberger, P. M.,Tuminello, W. H., Turner, T. F., New Low Temperature Performance GradingMethod Using 4 mm Parallel Plates on a Dynamic Shear Rheometer. TRBPreprint CD, 2011.

TABLE 1 Critical low Critical low Critical Low Critical Low temperatureCritical Low Critical Low temperature temperature temperature stiffnessgrade temperature temperature stiffness grade High grade based gradebased subtracted grade based grade based subtracted Bitumen temperatureon 4 mm DSR on 4 mm DSR from creep on 4 mm DSR on 4 mm DSR from creeptype & stiffness Stiffness, ° C., Creep, ° C. grade, ΔTc° C., Stiffness,° C., Creep, ° C. grade, ΔTc° C., source grade, ° C. 20 hr. PAV 20 hr.PAV 20 hr. PAV 40 hr. PAV 40 hr. PAV 40 hr. PAV PG 58-28 60.3 −31.4−30.9 −0.5 −30.7 −27.8 −2.9 PG 64-22 67.1 −27.1 −26.2 −.9 −25.8 −23.2−2.6 Binder Critical Low Critical Low Critical low recovered temperaturetemperature temperature from stiffness creep grade stiffness grade RAPgrade based based subtracted on 4 mm DSR on 4 mm DSR from creep grade,ΔTc° C. RAP 03- 85.0 −25.5 −22.3 −3.2 16-15-D RAP 02- 89.5 −25.3 −21.3−4.0 23-15-B RAP 03- 98.8 −22.4 −17.1 −5.3 24-15-D RAP 02- 87.5 −27.8−26.2 −1.6 09-15-B RAS 04- 158.2 −27.5 −0.3 −27.2 03-15-D RAS 02- 137.7−25.7 +9.7 −35.4 09-15-C

Table 2 shows the high and low temperature properties of blends producedwith virgin binder and bitumen recovered from post-consumer wasteshingles after different periods of aging. Also shown in Table 2 arehigh and low temperature properties of mixtures containing RAP anchorRAS. Some of these mixtures have undergone extended laboratory aging andsome are from field cores.

TABLE 2 Critical Low Critical Critical low temperature Low temperaturestiffness temperature stiffness grade Binder recovered from RAP Highgrade based creep grade subtracted from or RAS containing mixturestemperature on 4 mm based on 4 creep grade. either lab or field agedgrade DSR nun DSR ΔTc° C. Field mix 09-27-13-F PG 58- 83.1 −32.3 −30.6−1.7 28 + 5% RAS, unaged Field mix 09-27-13-E PG 58- 102.8 −28.5 −23.9−4.6 28 + 5% MS, 5 day aged @ 85° C. US Hwy 14 PG 58-28 + 6% 85.4 −30.9−24.1 −6.8 RAS & 11% RAP, 10 day aged @ 85° C. US Hwy 14 PG 52-34 + 6%80.8 −35.6 −29.9 −5.7 RAS & 11% RAP, 10 day aged @ 85° C. US Hwy 14 PG58-28 + 31% 79.5 −29.6 −26.7 −2.9 RAP, 10 day aged @ 85° C. Core fromfield paved 2011, 87.6 −25.9 −21.7 −4.2 cored 2013, binder from top ½inch of core (mix contained PG 58-28 + 5% RAS or 22% shingle binderreplacement) Core from field paved 2011, 86.0 −25.6 −21.9 −3.8 cored2013, binder from second ½ inch of core (mix contained PG 58-28 + 5% RASor 22% shingle binder replacement) Core from field paved 2011, 80.7−26.0 −24.2 −1.8 cored 2013, binder from layer 2 inches below surface(mix contained PG 58-28 + 5% RAS or 22% shingle binder replacement)

Tables 1 and 2 show the impact of incorporating high binder replacementlevels of recycled materials, especially those derived frompost-consumer waste shingles. The data demonstrate the desirability ofincorporating additives into bitumen and bituminous mixtures to mitigatethe impact of the bitumen from these recycled components and retardfurther oxidative aging of the total bitumen in the final mixture. Thelast three rows of Table 2 show that the further away from theair-mixture interface, tire lower the impact on ΔTc parameter. Thisparameter may be used to assess the impact of aging on hinder propertiesand more specifically the impact of aging on tire relaxation propertiesof the binder; the relaxation property is characterized by the propertyreferred to as “low temperature creep grade”.

Research published in 2011 showed, based on recovered binder data fromfield cores, that ΔTc could be used to identify when a pavement reacheda point where there was a danger of non-load related mixture crackingand also when potential failure limit had been reached. In that researchthe authors subtracted the stiffness-critical temperature from the creepor m-critical temperature and therefore binders with poor performanceproperties had calculated ΔTc values that were positive. Since 2011industry researchers have agreed to reverse the order of subtraction andtherefore when the m-critical temperature is subtracted from thestiffness critical temperature binders exhibiting poor performanceproperties calculate to ΔTc values that are negative. The industrygenerally agreed that to have poor performing binders become morenegative as performance decreased seemed more intuitive. Therefore,today in the industry and as used in the application, a ΔTc warninglimit value is −3° C., and a potential failure value is −5° C. In etherwords, −5° C. is more negative than −3° C. and therefore a ΔTc value of−5° C. is worse than a ΔTc value of −3° C.

Reports at two Federal Highway Administration Expert Task Group meetingshave shown a correlation between ΔTc values of binders recovered fromfield test projects and severity of pavement distress related to fatiguecracking. Additionally, it has been shown that when binders used toconstruct these field test projects were subjected to 40 hours of PAVaging, the ΔTc values showed a correlation to pavement distress relatedto fatigue cracking, especially top down fatigue cracking which isgenerally considered to result from loss of binder relaxation at thebituminous mixture surface.

It is therefore desirable to obtain bituminous mixtures with bitumenmaterials that have a reduced susceptibility to the development ofexcessively negative ΔTc values.

The data in Table 1 show typical virgin binders produced at refineriescan maintain a ΔTc of greater than −3° C. after 40 hours of PAV aging.Further, the data in Table 1 show that binder recovered from RAP canhave ΔTc values of less than −4° C., and that the impact of high RAPlevels in new bituminous mixtures should be evaluated. Further, theextremely negative values of ΔTc for RAS recovered binders requireadditional scrutiny as to the overall impact of RAS incorporation intobituminous mixtures.

Table 2 shows that it is possible to age bituminous mixtures underlaboratory aging followed by recovery of the binder from the mixturesand determination of the recovered binder ΔTc. The long term agingprotocol for bituminous mixtures in AASHTO R30 specifies compacted mixaging for five days at 85° C. Some research studies have extended theaging time to ten days to investigate the impact of more severe aging.Recently, aging loose bituminous mixes at 135° C. for 12 and 24 hoursand in some instances for even greater time periods have been presentedas alternatives to compacted mix aging. The goal of those agingprotocols is to produce rapid binder aging similar to field agingrepresentative of more than five years in service and more desirablyeight to 10 years in service. For example, it has been shown formixtures in service for around eight years that the ΔTc of the reclaimedor recycled asphalt from the top ½ inch of pavement was more severe than12 hours aging at 133° C. but less severe than 24 hours aging at 135° C.

The data in the first two rows of Table 2 show why long-term aging ofmixtures containing recycled products is important. The binder recoveredfrom the unaged mix (row 1) exhibited a ΔTc of −1.7° C., whereas thebinder recovered from the 5 day aged mix exhibited a ΔTc of −4.6° C.

Pure Sterol:Crude Sterol Blends

The disclosed sterol blends (pure sterol:crude sterol) can alter (e.g.,reduce or retard) an asphalt binder aging rate, or can remote or renewan aged or recycled binder to provide some or ail of the properties of avirgin asphalt binder. For example, the sterol blends can alter orimprove physical and rheological characteristics such as stiffness,effective temperature range, and low tempera-tire properties of theasphalt binder.

In some embodiments, the sterol blend belongs to the class oftriterpenoids, and in particular to sterols or stanols. The disclosedblends (e.g. triterpenoids) can effectively work with asphaltenes.Asphaltenes include extensive condensed ring systems with some level ofunsaturation. The asphaltene content of typical binders can range fromless than 10% to more than 20%. Asphaltenes are typically described asmaterials that are insoluble in n-heptane. An exact structure is unknownand based on the performance behavior of different binders it isunlikely that the asphaltene structure in any two binders is the same,especially those front different crude sources. Asphaltenes give abanter its color and stiffness and they increase in content as thebinder ages. Consequently, the addition of RAP and/or RAS causes theasphaltene content to increase. Increasing asphaltene content along withother product of oxidation such as carbonyls and sulfoxides areresponsible for the stiffening of bituminous mixtures and their ultimatefailure. By their very chemical nature asphaltenes are not readilysoluble in aliphatic chemicals. Aromatic hydrocarbons will readilydissolve asphaltenes and aromatic process oils have been used inrecycled mixtures. However these oils may contain poly nuclear aromaticcompounds including listed potential carcinogens and therefore are notdesirable additives Most plant based oils are straight or branched chainhydrocarbons with some level of unsaturation and therefore are not aseffective at retarding aging as they are at softening the overallhinders in a mixture.

Triterpenoids are a major group of plant natural products that includesterols, triterpene saponins, and related structures. Triterpenoids canbe of natural or synthetic origin. Typically they are obtained byextraction from plant material. Extraction processes for the isolationof triterpenoids are described e.g. in the international applications WO01/72315 A1 and WO 20001/016336 A1, the disclosures of which are eachincorporated here by reference in their entirety.

The triterpenoids include plant sterols and plant stanols. The disclosedtriterpenoids refer to the non-esterified forms of any of the plantsterols mentioned herein.

Exemplary pure plant sterols include campesterol, stigasterol,stigmasterol, β-sitosterol, Δ5-avenosterol, Δ7-stigasterol,Δ7-avenosterol, brassicasterol or mixtures thereof. In some embodiments,the sterol blend contains β-sitosterol as the pure sterol. In otherembodiments, live sterol blend contains a mixture of pure sterols.Commercially available pure sterols and mixtures of pore sterolsincludes those available from MP Biomedicals (Catalog No. 02102886)referred to as beta-Sitosterol (beta-Sitosterol ˜40-60%; campesterol˜20-40%; Stigmasterol ˜5%). In some embodiments, a pure sterol can haveat least 70 wt. % sterols, and in some embodiments can have at least 80wt %, at least 85 wt % or at least 95 wt % sterols.

Exemplary crude plant sterols include modified or unmodified naturalproducts containing significant quantities of sterols, including suchdiverse plant sources as corn oil, wheat germ oil, sarsaparilla root,soybean pitch and corn oil pitch. For example, tall oil pitch isobtained dicing the process of preparing paper from wood, particularlypine wood. Tall oil pitch is an extremely complex material that cmcontain rosins, fatty acids, oxidation products and esterifiedmaterials, an appreciable fraction of which are sterol esters Plantsources of erode sterols are inexpensive in that they are the foots ortailings left from various manufacturing processes

In some embodiment, the erode sterol sources include stigmasterol,β-sitosterol, campesterol, ergosterol, brassicasterol, cholesterol andlanosterol or mixtures thereof. In some embodiments, the crude sterolsources include soy bean oil, corn oil, rice bran oil, peanut oil,sunflower seed oil, safflower oil, cottonseed oil, rapeseed oil, coffeeseed oil wheat germ oil, tail oil, and wool grease. In some embodimentsthe crude sterol includes a bio-derived source or partially distilledresidue of the bio-derived source. In some embodiments, the erode sterolsource includes tall oil pitch, soybean oil or corn oil.

Any of lire oil tailings or pitches from the disclosed plant sources aresuitable crude sterol sources. U.S. Pat. No. 2,715,638, Aug. 16, 1955,to Albrecht, discloses a process for recovering sterols from tail oilpitch whereby the fatty acid impurities are removed by a neutralizationprocess. Following this, the sterol esters are saponified; the freesterols are then recovered and washed with isopropanol and dried. Ifsufficiently purified, the recovered free sterols may be used as puresterols rather than as crude sterols in the disclosed pure sterol:crudesterol blends.

The crude sterols preferably are obtained from plant sources. The erodesterol can include components in addition to the desired sterol orsterols. Exemplary plant sources for crude sterols include tall oilpitch, crude tail oil, sugar cone oil, hot well skimmings, cottonseedpitch, soybean pitch, corn oil pitch wheat germ oil or rye germ oil. Insome embodiments, tall oil pitch is a source of the erode sterol. Talloil pitch can include about 30 to 40% unsaponifiable molecules.Unsaponifiables are molecules that do not react with alkali hydroxides.Fatty and rosin acids remaining is the tall oil pitch readily react withpotassium or sodium hydroxides and thus the unsaponifiables can bereadily separated. It has been shown that 45% of the unsaponifiablefraction can include sitosterols. Therefore, a tall oil pitch sample cancontain approximately 13.5% to 18% sterol molecules by weight. In someembodiments the crude sterol can have less than a food grade of purity(e.g., less than 85 wt. % sterols) or containing more than 85 wt %sterols but also containing impurities or contaminants that render thematerial unsuitable for use in foods.

In some embodiments, the erode sterol may be animal derived such ascholesterol.

The pure sterol:crude sterol blend added to the asphalt composition mayfor example range from about 0.5 to about 15 wt %, or about 1 to about10 wt. %, about 1 to about 3 wt. % of the virgin binder in an asphaltcomposition. The sterol blends can in some embodiments include a 10:90to 90:10 ratio of pure sterol to crude sterol. The sterol blends can insome embodiments include at least a 20:80, 30:70 or 40:60 ratio of puresterol to crude sterol, and in some embodiments can include less than an80:20, 70:30 or 60:40 ratio of pure sterol to erode sterol.

In some embodiments, pore sterol:crude sterol blend can alter, reduce orretard the degradation of rheological properties in binder containingrecycled bituminous materials that include softening agents such as RAS,RAP, REOB, virgin paraffin or naphthenic base oils, untreated ornon-refined waste drain oils or waste engine oil materials, vacuum towerasphalt extenders, paraffinic or naphthenic processing oils orlubricating base oils. In some embodiments, the sterol blend when usedin an asphalt or asphalt pavement maintains a ΔTc value greater than orequal to −5° C. as the asphalt or asphalt pavement is aged.

In some embodiments, the pure sterol:crude sterol blends can provide anasphalt binder composition with a ΔTc of greater than or equal to −5.0°C. In some embodiments, the sterol blends can provide art asphalt binderwith a ΔTc of greater than or equal to −5.0° C. after 40 hours of PAVaging. In still other embodiments, the disclosed sterol blend canprovide an asphalt binder with a less negative ΔTc value and a decreasedR-Value following aging, when compared to a similarly-aged asphaltbinder without the sterol blend.

Softening Agents & Other Additives

Softening agents that may be used in binders include waste engine oiland waste engine oil that may be further processed to provide REOB. REOBis a low cost softening additive and asphalt extender obtained from theresidual material remaining after the distillation of waste engine oileither under vacuum or at atmospheric pressure conditions. The distilledfraction from the rerefining process is reprocessed into new lubricatingoil for vehicles, but the bottoms do not have an available market due tothe presence of metals and other particulates from internal combustionengines. Also these bottoms contain paraffinic hydrocarbons andadditives incorporated into the original lubricating oil. For many yearsREOB were used by some companies as an asphalt extender, hut the usagewas localized.

Greater amounts of waste engine oils are being produced and sold as REOBinto the asphalt binder market. The use of REOB may provide mixtures,which when aged, have ΔTc values of −4° C. or lower with consequent poorperformance in pavements. When REOB are added to some asphalts at levelsas low as 5% by weight, the resulting ΔTc after 40 hr. PAV aging can be−5° C. or lower (viz., more negative). Recovered binders from fieldmixes shown to contain REOB by means of metals testing have showngreater distress than field mixtures of the same age and the sameaggregate and paved at the same lime but not containing REOB.

The disclosed pure sterol:crude sterol blends can mitigate the impact ofwaste engine oils (e.g. REOB) on ΔTc (as evaluated, for example, using40 hr. PAV) and renew or retard the aging rate of the recycled asphalt.

The disclosed sterol blend can also be used to mitigate the impact ofother softening agents. These other softening agents include syntheticor virgin lubricating oils (such as MOBIL™ 1 synthetic oil fromExxonMobil Corp, and HAVOLINE™ 10W40 oil from Chevron USA Inc. h virginparaffin or naphthenic base oils, untreated or non-rerefined waste drainoils or waste engine oil materials, vacuum tower asphalt extenders (thenon-distillable fraction from re-re lining used engine oil) andparaffinic or naphthenic process oils.

The asphalt composition may contain oilier components in addition to thedisclosed sterol blend. Such other components can include elastomers,non-bituminous binders, adhesion promoters, softening agents,rejuvenating agents and other suitable components.

Useful elastomers include, for example, ethylene-vinyl acetatecopolymers, polybutadienes, ethylene-propylene copolymers,ethylene-propylene-diene terpolymers, reactive ethylene terpolymers(e.g. ELVALOY™), butadiene-styrene block copolymers,styrene-butadiene-styrene (SBS) block terpolymers, isoprene-styreneblock copolymers and styrene-isoprene-styrene (SIS) block terpolymers,chloroprene polymers (e.g., neoprenes) and the like. Cured elastomeradditives may include ground tire rubber materials.

Conventional rejuvenating agents are classified into types such as RA-1,RA-5, RA-25, and RA-75 as defined by ASTM D4552. Rejuvenating agents foruse in the disclosed asphalt compositions may for example resemble themaltene fraction of asphalt such as an RA-1 rejuvenating agent, an RA-5rejuvenating agent, or mixtures thereof. Exemplary rejuvenating agentsare available from Holly Frontier under their HYDROLENE™ brand asphaltoils, from American Refining Group, Inc. under their KENDEX™ brand orfrom Tricor Refining, LLC under their Golden Bear Preservation ProductsRECLAMITE™ brand. Asphalt oils meeting ASTM standard D4552, andclassified as RA-1 are suitable for harder asphalts, such as PG 64.RA-5, RA-25 and RA-75 oils may also be used with lower viscosityasphalts, such as PG 52. The rejuvenation agents can also includerecycling agents that are rich in aromatics and resins, with smallamounts of saturates.

The disclosed asphalt compositions can be characterized according tomany standard tests such as those recited in applicable ASTMspecifications and test methods. For example, the disclosed compositionscan be characterized using rheological tests (viz., dynamic shearrheometer, rotational viscosity, and bending beam).

At low temperatures (e.g., −10° C.), road surfaces need crackingresistance. Under ambient conditions, stiffness and fatigue propertiesare important. At elevated temperatures, roads need to resist ruttingwhen the asphalt becomes too soft. Criteria have been established by theasphalt industry to identify rheological properties of a binder thatcorrelate with likely paved road surface performance over the threecommon sets of temperature conditions.

In one embodiment, the binder includes a blend of binders. In certainembodiments, the binder blend includes virgin binder and binderextracted front reclaimed asphalt. For example, the binder extractedfrom RAS material may be extracted from manufacturer asphalt shinglewaste, from consumer asphalt shingle waste, or from a mixture of bindersextracted from manufacturer and consumer asphalt shingle waste. In someembodiments, a binder blend may include virgin binder and recycledbinder. The virgin binder can be from about 60 wt % to about 95 wt % ofthe binder blend and from about 2 wt % to about 100 wt % of reclaimedasphalt such as RAS. In certain embodiments, the binder blend includesthe addition of a sterol blend from about 0.5 wt % to about 15.0 wt % ofthe virgin asphalt. In some embodiments, the binder blend can includethe addition of from about 0.2 wt % to about 1.0 wt % pure sterol:crudesterol blend. The sterol blend has been shown to improve high and lowtemperature properties and PG grading for both low and high temperatureends of RAS-containing asphalt hinder blends.

The asphalt binder composition may be prepared by mixing or blending thepure sterol:crude sterol blend with the virgin binder to form nbituminous mixture or blend. The bituminous mixture or blend can beadded to recycled asphalt (e.g., RAS and/or RAP) and aggregate. One ofskill in the art will recognize that any sequences of adding and mixingcomponents are possible.

Asphalt compositions can be prepared by applying mechanical or thermalconvection. In one aspect, a method of preparing an asphalt compositioninvolves mixing or blending a pure sterol:crude sterol blend with virginasphalt at a temperature of from about 100° C. to about 250° C. in someembodiments, the sterol blend is mixed with the virgin asphalt at atemperature from about 125° C. to about 175° C., or 180° C. to 205° C.In some embodiments, the asphalt composition is mixed with asphalt,sterol blend and softening agent. In still other embodiments, theasphalt composition is mixed with asphalt, RAS, sterol blend andaggregate.

To determine the ΔTc parameter, a 4 mm DSR tea procedure and dataanalysis methodology from the Western Research Institute was employed asnoted above. The DSR test procedure and methodology are also disclosedin International Application No. PCT/US16/37077 filed Jun. 10, 2016 andin PCT/US2016/064950 filed Dec. 5, 2016 and PCT/US2016/064961 filed Dec.5, 2016, each of which is incorporated herein by reference in itsentirely.

The ΔTc parameter can also be determined using a Bending Beam Rheometer(BBR) test procedure based on AASHTO T313 or ASTM D6648. It is importantthat when the BBR test procedure is used that the test is conducted at asufficient number of temperatures such that results for the Stiffnessfailure criteria of 300 MPa and Creep or re-value failure criteria of0.300 are obtained with one result being below the failure criteria andone result being above the failure criteria. In some instances forbinders with ΔTc values less than −5° C. this can require performing theBBR test at three or more test temperatures. ΔTc values calculated fromdata when the BBR criteria requirements referred to above are not metmay not be accurate.

Pavement surface characteristics and changes in them can be revealed inan asphalt composition. These surface characteristics can be determinedusing atomic force microscopy (AFM). AFM is described for example in R.M. Overney. E. Meyer, J. Frommer, D. Brodbeck, K, Lüthi, L. Howald,H.-J. Güntherodt, M. Fujihira, H. Takano, and Y. Gotoh, “FrictionMeasurements on Phase Separated Thin Films with a Modified Atomic ForceMicroscope”, Nature, 1992, 359, 133-135; E. zer Muhlen and H. Niehus,“Introduction to Atomic Force Microscopy and its Application to theStudy of Lipid Nanoparticles”, Chapter 7 in Particle and SurfaceCharacterization Methods, R. H. Muller and W. Mehnert Eds, MedpharmScientific Pub, Stuttgart, 1997; and in H. Takano, J. R. Kenseth. S.-S.Wong, J. C. O'Brien, M. D. Porter, “Chemical and Biochemical AnalysisUsing Scanning Force Microscopy”, Chemical Reviews 1999, 99, 2845-2890.

AFM is a type of scanning microscopy that provides high resolution,three-dimensional imaging at the atomic and molecular level. AFM can beused for both topographical imaging and force measurements.Topographical imaging involves scanning the cantilever/tip across thesample surface. A laser beam k reflected off the hack of the cantilever,and small changes in cantilever deflection are detected with aposition-sensitive photodiode detector. This deflection is processed bythe system electronics to determine topological height changes on thesample surface.

The surface defects may be measured as the surface roughness, expressedas average roughness over an image surface, based on the average heightof the roughness extending out of the surface of the sample expressed inμm, and with the defect area (i.e. the non-smooth plane of the sample)expressed in μm² and as a percent of the image area (e.g., as a percentof a 400 μm² image area). AFM can be used to determine the effects ofthe sterol blends on an asphalt composition, and was used to determinethe effects of pure sterols on asphalt compositions in theabove-mentioned International Application No. PCT/US16/37077 andPCT/US2016/064950 filed Dec. 5, 2016 and PCT/US2016/064961 filed Dec. 5,2016.

Binders can be prepared for AFM by application of a small bead to asteel stub. With a knife, the bead can be scraped against the surface ofthe stub and the resulting film heated to 115° C. for about 2 min toallow the film surface to level. AFM images can be captured at roomtemperature on a Bruker Dimension Icon-PT™ Scanning Probe microscope.Both topographic and friction images can be obtained after the asphaltfilms have been annealed 72 h to 96 h at room temperature. Antimonydoped silicon cantilever tip AFM probes (Bruker Corporation) can be usedfor measurements. Topographic images can reveal vertical elevations anddeclinations associated to surface features, whereas the friction imageallows for differentiation of surface material based on changes inelastic or adhesive properties.

In some embodiments, a method for identifying aging in an asphaltcomposition and slowing the aging or restoring the aged asphalt includesanalyzing an asphalt composition for the presence or absence of surfacedefects, wherein the asphalt is determined as aging if minimal surfacedefects are detected; and adding a pure sterol:crude sterol blend andvirgin binder to the aged asphalt binder composition to reduce or slowthe aging. In some embodiments, the aged asphalt compositions includerecycled asphalts, softening agents, and rejuvenating agents. Forexample, some asphalt compositions include RAS, RAP, REOB, virginparaffinic or naphthenic base oil, untreated or non-rerefined wastedrain oils or waste engine oil materials, vacuum tower asphaltextenders, paraffinic or naphthenic processing oils and lubricating baseoils. In some embodiments, the average roughness of an asphaltcomposition with sterol blend is 1.5 to 350 μm from 3.6 to 232 μm, orfrom 10 to 230 μm.

The present application is further illustrated in the followingnon-limiting examples, in which all parts and percentages are by weightunless otherwise indicated.

Example 1

To investigate the efficacy of blends of crude sterol and pure sterolcompared to only pure sterol on the aging properties of binderscontaining REOB, a PG 64-22 base asphalt was used. The various sampleswere aged for 20 and 40 hours in the PAV following ASTM D65217 and byRFTO following ASTM D2872.

Blends were produced by mixing the components with a low shear LIGHTNIN™mixer from SPX Flow Corp. in a 1 gallon can at a temperature of 187.8°C.-204° C. (370-400° F.) for approximately 30 minutes.

The blend components included 92% of 64-22 binder, 8% REOB and variousconcentrations of sterols provided as blends of crude sterol in the formof tall oil pitch (obtained from Union Camp) and pure sterol (obtainedfrom MP Biomedical).

It was assumed that the sterol in crude sterol sources such as tail oilpitch includes about 15% sterol. Therefore, the following samples wouldinclude expected sterol amounts as follow's:

-   -   1. 85% tall oil pitch+15% pure sterol; sterol amount is        (0.85*15) from tall oil pitch+15 from pure sterol=27.7% expected        sterol.    -   2. 60% tall oil pitch+40% pure sterol; sterol amount is (0.6*15)        from tall oil pitch+40 from pure sterol=49% expected sterol.    -   3. 30% tall oil pitch+70% pure sterol; sterol amount is (0.3*15)        from tall oil pitch+70 from pure sterol=74.5% expected sterol.

If 10% of each of the above blends were added to PG 64-22 containing 8%REOB, it would be expected that (based on the assumption of 15% sterolin the tall oil pitch) the blends would contain 2.8% sterol, 4.9% steroland 7.4% sterol.

The results are shown below in Table 3.

TABLE 3 % Tall oil Ratio of Pitch and tall oil Low High % REOB PureSterol pitch to S- m- temp Temp Binder added to blend added SterolCritical Critical PG PG Aging binder to binder TOP/Sterol Temp temp ΔTcGrade Grade¹ Unaged 8 0 0/0 −36.1 −38.2 2.10 −36.1 63.2 Unaged 8 1085/15 −38.20 −39.26 1.06 −38.2 56.4 Unaged 8 10 60/40 −36.29 −38.27 1.98−36.29 56.9 Unaged 8 10 30/70 −34.20 −37.51 3.30 −34.20 57.0 RTFO 8 00/0 −35 −35.60 0.60 −35.0 64.0 RTFO 8 10 85/15 −35.666 −36.394 0.73−35.67 57.1 RTFO 8 10 60/40 −34.90 −35.92 1.03 −34.90 57.1 RTFO 8 1030/70 −33.05 −35.55 2.49 −33.05 57.3 20 hr. 8 0 0/0 −34.56 −30.92 −3.64−30.92 82.5 PAV 20 hr. 8 10 85/15 −33.045 −31.231 −1.81 −31.23 75.1 PAV20 hr. 8 10 60/40 −32.32 −30.46 −1.86 −30.46 75.2 PAV 20 hr. 8 10 30/70−30.52 −29.65 −0.87 −29.65 74.3 PAV 40 hr. 8 0 0/0 −30.94 −24.48 −6.46−24.48 95.1 PAV 40 hr. 8 10 85/15 −32.345 −27.681 −4.66 −27.681 83.2 PAV40 hr. 8 10 60/40 −30.75 −27.18 −3.57 −27.18 81.8 PAV 40 hr. 8 10 30/70−28.40 −26.36 −2.05 −26.36 80.4 PAV 60 hr. 8 10 85/15 −30.42 −22.98−7.44 −22.98 89.9 PAV 60 hr. 8 10 60/40 −30.48 −25.40 −5.08 −25.40 87.4PAV 60 hr. 8 10 30/70 −28.52 −25.60 −2.91 −25.60 84.1 PAV ¹For unagedbinder the high temperature grade is where binder stiffness = 1 KPa, forRTFO the high temperature grade is where binder stiffness = 2.2 KPa, forPAV residues the high temperature grade is where the binder stiffness =1 KPa.

FIG. 4 is a plot of the data shown in Table 3 for the stiffness criticaltemperatures, m-value critical temperatures and ΔTc values. The dataplotted in FIG. 4 shows that the blends of tall oil pitch and puresterol improve the ΔTc values of the PG 64-22 with 8% REOB relative tothe blend with no tall oil pitch and sterol. There appears to be a doseresponse of total sterol in the blends and general degrading of ΔTc asthe binder aging progresses, however, higher levels of total sterol inthe blend maintain acceptable ΔTc properties even after 60 hours of PA Vaging.

Table 4 shows the independent effect of each tall oil pitch blended intoasphalt; pure sterol blended into asphalt; and blends of tall oil pitchwith pure sterol on 20 and 40 hour PAV aging on those blends in PG64-22+8% REOB.

TABLE 4 Binder % % Tall % S_critical m_critical Low Temp Aging REOB OilPitch¹ Sterol² Temp Temp sΔTc PG Grade 20 hr. 8 0 0 −34.6 −30.9 −3.64−30.92 PAV 20 hr. 8 5 0 −31.48 −28.97 −2.51 −28.97 PAV 20 hr. 8 10  0−33.11 −30.62 −2.49 −30.62 PAV 20 hr. 8 0 2.5 −32.3 −29.4 −2.84 −29.43PAV 20 hr. 8 0 5 −29.7 −28.4 −1.27 −28.42 PAV 20 hr. 8 0 7.5 −31.4 −29.5−1.87 −29.52 PAV 20 hr. 8 10% of 85/15 2.7 −33.05 −31.23 −1.81 −31.23PAV blend 20 hr. 8 10% of 60/40 4.9 −32.32 −30.46 −1.86 −30.46 PAV blend20 hr. 8 10% of 30/70 7.4 −30.52 −29.65 −0.87 −29.65 PAV blend 40 hr. 80 0 −30.9 −24.5 −6.46 −24.48 PAV 40 hr. 8 5 0 −29.86 −24.39 −5.47 −24.39PAV 40 hr. 8 10  0 −30.79 −26.38 −4.41 −26.38 PAV 40 hr. 8 0 2.5 −31.1−25.9 −5.20 −25.88 PAV 40 hr. 8 0 5 −29.6 −26.6 −2.93 −26.62 PAV 40 hr.8 0 7.5 −30.4 −28.4 −2.05 −28.38 PAV 40 hr. 8 10% of 85/15 2.7 −32.34−27.68 −4.66 −27.68 PAV blend 40 hr. 8 10% of 60/40 4.9 −30.75 −27.18−3.57 −27.18 PAV blend 40 hr. 8 10% of 30/70 7.4 −28.40 −26.36 −2.05−26.36 PAV blend ¹10% of 85/15 refers to 10% addition of a blend of 85%tall oil pitch and 15% pure sterol by weight, 10% of 60/40 refers to 10%addition of a blend of 60% tall oil pitch and 40% pure sterol by weight,and 10% of 30/70 refers to 10% addition of a blend of 30% tall oil pitchand 70% pure sterol by weight. ²The sterol concentrations listed for theblends of tall oil pitch and pure sterol are estimates of total sterolsbased on the assumption that the tall oil pitch contains 15% sterol byweight.

Examination of the data in Table 4 shows for the 20 hour PAV residuethat for the 5% and 10% tall oil blends and the 2.5% pure sterolcomposition the ΔTc values are similar and are approximately 1° C.warmer than for the 8% REOB blend in PG 64-22 with no other additive.This implies a minor impact of those blends on the degrading impact ofthe 8% REOB on the binder. The ΔTc data for the 20 hour PAV residuesproduced with the 10% dosage of tall oil pitch plus pure sterol showedresults that are approximately 1° C. warmer than the tall oil only orthe pure sterol only blends. For the 40 hour PAV residues the 5% anti10% tall oil blends and the 2.5% pure sterol composition show similarresults and all show ΔTc values that are 1-2° C. warmer than the64-22+8% REOB blend. The 5% and 7.5% pure sterol blends have ΔTc valuesthat are 3.5-4.5° C. warmer than the 64-22+REOB blend. At the 40 hourPAV the blends of tall oil pitch and pure sterol exhibit ΔTc propertiessimilar to the pure sterol blends, indicating that it is possible toobtain outcomes similar to those achieved using the pure sterol byblending pure sterol with a bio derived oil or bio derived oil pitchresidue containing less than pure sterol.

FIG. 5 graphically shows this relationship between the ΔTc results forpure sterol and blends with tall oil pitch and pure sterol using the PG64-22 base binder plus 8% REOB. FIG. 5 shows foe similarity in ΔTcbehavior at 20, 40 and 60 hours of PAV aging for these two sets ofmaterials. There is no 60 hour PAV data provided for the 64-22+8% REOB,but it is clear that the lowest dosage levels of sterol have ΔTc valuesat 60 hours that are comparable to the ΔTc results for the non-sterolblend at the 40 hour PAV level.

Example 2

To investigate the effects of pure sterol crude sterol blends on theaging properties of binders, 20 hour PAV aged RAPs were used. The 20hour aged RAPs were each aged in the PAV (Pressured aging vessel)following ASTM D65217. The RAPs were blended with either 5% of a bio-oilfrom Cargill, MN (Cargill 1103) or with 5% of a pure sterol blend. EachRAP was tested before mixing with the various sterol blends.

Blends were produced by mixing the components in a 3 ounce tin can. Thetin cans were covered and placed in a 60° C. (140° F.) oven overnight toallow for warming and mixing of the components. After the overnightwarming, the samples were hand mixed and tested for high temperaturestiffness properties with a 25 nm DSR test procedure and low temperatureproperties wore determined using the 4 mm DSR testing procedure. Theresults are reported in Table 5.

TABLE 5 % % HT LT improvement R- improvement Blend PG PG ΔTc in ΔTcvalue in R value CTH N RAP PAV, original test 85.6 −21.2 −5.4 2.78 CTH NRAP PAV 85.9 −21.7 −6.5 2.77 Average of original and 85.8 −21.5 −6.02.78 new test of untreated sample CTH N RAP PAV + 5% Cargill 76.2 −31.3−4.9 17.5% 2.73 1.53% 1103 Plt 77 RAP PAV original test 89.8 −19.9 −4.12.61 Plt 77 RAP PAV 91.2 −18.0 −4.7 2.74 Average of original and 90.5−19.0 −4.4 2.67 new test of untreated sample Plt 77 RAP PAV + 5% Sterols84.6 −20.4 −1.2 72.3% 2.26 15.35%

The results in Table 5 show the bio oil reduced the high temperaturegrade of the RAP by 9.6° C. and dropped the low temperature PC grade by9.8° C. The ΔTc value was improved by 1.1° C. or 17.5% while the R-valuewas decreased by only 1.53%, indicating that the addition of thesoftening oil did little to improve the tow temperature relaxationproperties of the RAP binder. The addition of the sterol reduced thehigh temperature grade by 5.9° C., and dropped the low temperature gradeby 1.6° C., but the ΔTc value was increased by 3.2° C. or 72.3% whilethe R-value decreased by 15.35%. These comparative data indicate thatthe sterol addition is doing more than just softening the RAP.

The invention claimed is:
 1. A method for retarding the aging of orrestoring aged asphalt binder comprising: adding a pure sterol:crudesterol blend to an asphalt binder composition, wherein the asphaltbinder composition comprises a virgin asphalt binder, aged asphaltbinder or both, and wherein the sterol blend is 0.5-15 wt % of theasphalt binder composition and retards the aging rate of the asphaltbinder composition compared to a similarly aged asphalt bindercomposition that does not include the sterol blend.
 2. The method ofclaim 1, wherein the sterol blend comprises a 10:90 to 90:10 weightratio of pure sterol to crude sterol.
 3. The method of claim 1, whereinthe crude sterol comprises a bio-derived source or distilled residue ofthe bio-derived source.
 4. The method of claim 1, wherein the crudesterol comprises a tall oil pitch, soybean oil or corn oil.
 5. Themethod of claim 1, wherein the sterol blend is 1 to 10 wt. % of theasphalt binder composition.
 6. The method of claim 1, wherein the virginbinder is from 60 wt % to 95 wt % of the asphalt binder composition. 7.The method of claim 1, wherein the aged binder is 2 wt % to 100 wt % ofthe asphalt binder composition.
 8. The method of claim 1, wherein theasphalt binder composition further comprises a softening agent.
 9. Themethod of claim 8, wherein the softening agent further comprisesbio-derived or petroleum-derived oil.
 10. The method of claim 1, whereinthe aged asphalt binder comprises asphalt binder from reclaimed asphaltshingles or reclaimed asphalt pavement.
 11. The method of claim 1,wherein the sterol blend comprises an amount effective to provide a lessnegative ΔTc value and a decreased R-Value of an aged asphalt bindercomposition compared to a similarly-aged asphalt binder without thesterol blend.
 12. The method of claim 1, further comprising mixingaggregate with the asphalt binder composition, applying the resultingmixture to a base surface, and compacting the applied mixture.
 13. Anasphalt binder composition comprising virgin binder, aged asphalt bindercomprising reclaimed asphalt pavement (RAP), reclaimed asphalt shingles(RAS), or combinations of both, and a pure sterol:crude sterol blend,wherein the sterol blend is 0.5-15 wt % of the asphalt bindercomposition and retards the aging rate of the asphalt binder compositioncompared to a similarly aged asphalt binder composition that does notinclude the sterol blend.
 14. The asphalt binder composition of claim13, wherein the virgin binder can be from 60 wt % to 95 wt % of theasphalt binder composition.
 15. The asphalt binder composition of claim13, wherein aged binder can be 2 wt % to 100 wt. % of the asphalt bindercomposition.
 16. The asphalt binder composition of claim 13, wherein thesterol blend comprises a 10:90 to 90:10 weight ratio of pure sterol tocrude sterol.
 17. The asphalt binder composition of claim 13, whereinthe crude sterol comprises a bio-derived source or distilled residue ofthe bio-derived source.
 18. The asphalt binder composition of claim 13,wherein the crude sterol comprises a tall oil pitch, soybean oil or cornoil.
 19. The asphalt binder composition of claim 13, wherein the asphaltbinder composition further comprises a softening agent.
 20. The asphaltbinder composition of claim 13, further comprising aggregate with theasphalt binder composition to result in a mixture that is applied andcompacted to base surface.